diff --git a/tools/niminst/makefile.nimf b/tools/niminst/makefile.nimf
index d14960ac546e..a0e9a40f7de8 100644
--- a/tools/niminst/makefile.nimf
+++ b/tools/niminst/makefile.nimf
@@ -164,7 +164,7 @@ ifeq ($(ucpu),riscv64)
   mycpu = riscv64
 endif
 ifndef mycpu
-  $(error unknown processor: $(ucpu))
+  $(error unknown CPU architecture: $(ucpu) See makefile.nimf)
 endif
 
 # for osA in 1..c.oses.len: